Ben Cherry, web developer at Twitter, takes us step by step through the Module Pattern. He introduces the standard features of Anonymous Closures and avoiding global scope, and covers advanced concepts such as augmentation, cloning, inheritance, private state and sub-modules.

Douglas Crockford discusses how to create private members and methods, and using privileged methods to bridge the gap between public and private. It also contains the simplest and most understandable definition of closures I've ever seen.